The 2012 SL gets an improved twin-turbo V8 and a weight reduction, but what does that mean to the driver?

Can you sensibly compare a new car with a 50-year-old one? Depends on the terms of comparison. Enthusiast terms are not necessarily those of the mainstream motoring public, nor even those of generous means able to afford some expensive motoring indulgence. They are more concerned with the car as pleasure machine, as generator of driving-induced serotonins, than with notions of status and politically-correct technological advance.

Forget what a car says about you. What a car does for your own quality of life is much more important. This navel-gazing train of thought has come about because I have just driven, within minutes of each other, a brand new, just-launched Mercedes-Benz 500SL whose twin-turbo V8 makes 435bhp from its 4663cc, and a 300SL from half a century ago.

The new one is yours for around $116,000, and thanks to a structure that's all-aluminium apart from the windscreen-pillar reinforcements it weighs around 140kg less than the outgoing SL. That structure includes cast aluminium bulkheads, a feature I've not known of in a road car since the Gregoire-based Dyna Panhard of the early 1950s, although I'm sure someone will prove me wrong.

Other clevernesses in this sixth generation of SL involve magic: the optional Magic Sky glass panel in the folding magnesium roof, electrochromic to create transparency or opacity at whim, and Magic Vision Control, which is rows of opposing washer jets built into the wiper blades and switching squirt direction as the blades reverse their motion. No more soaking of SL occupants when screenwashing with the roof down.

There seems to be further magic in the claim of an official 31.0 mpg on the fantasyland official test cycle, a result helped by the seven gears in the automatic gearbox and the stop-start system, but that's no harder to credit than the 41.5 mpg accorded to the other member of the new SL range, the V6-engined SL350. In combined-cycle mpg world, everything is relative.

This new SL is craggier around the face than the decade-old last one, more flamboyant in its sculpting, more shameless in its vent-references to the 1950s original. Will it be the epitome of sports-car art half a century on, as its ancestor is now? I suspect not; but for now, let's see how the SL500 drives.

It's fast, very. From nothing to 62mph takes 4.6 seconds, a pace delivered with the ferocity, and much of the soundtrack, of that most likeable of previous-gen SLs, the supercharged SL55 AMG. It seems almost incongruous here, given the soft-edged opulence of the surroundings, but a throttle response bordering on the violent –especially in the transmission's sport mode – leaves no doubt as to the torrent of torque on offer (516lb ft of it).

This car is all about lunges of movement, especially if you have the optional Active Body Control (ABC) suspension. This is not a new system, but it sounds intriguing with its constant self-levelling of pitch and roll and theoretically faultless flattening of crests and filling-in of dips. It uses very stiff coil springs as the base springing medium, with concentric electrohydraulic actuators to aid or oppose the springs' efforts as required.

Two snags. The ABC, especially in combination with the standard-fit 'Direct-Steer' which progressively speeds off-center the steering response, puts a kind of synthetic filter between you and what's really happening at the wheels. And the combination of the darty steering, frantic throttle and the ABC's unexpected inability to cope with short undulations makes this SL500 a hard car to conduct with any fluidity. Abrupt motion-checks over the undulations cause an involuntary prod on the accelerator, resulting in a lunge forward which can turn into a malign loop of positive feedback until you back off completely.

There are shades of SLR McLaren here in the exaggerated pointability combined with a feeling of detachment from the action, and it's quite odd. However, the new structure's rigidity is mighty impressive, as is the sound quality from the FrontBass speaker units which use the volumes between toeboard and bulkhead as the resonance chambers.

Forget ABC, then. Far better to drive an SL with the regular suspension whose only gizmology is the adaptive dampers. This comes in standard or, matched to AMG styling exaggerations, Sport form, and it makes a vastly better SL Now it flows properly over bumps, you can place it more intuitively in bends, and the steering and throttle alertness can be enjoyed for what they are. It works best with suspension set to Comfort and transmission to E (that is, normal mode); the dampers' adaptive ability and the V8's torque give all the stimulation you reasonably need unless you want to venture into the swift- and smooth-shifting world of paddle-triggered manual shifts.

In the right form and the right modes, then, the new SL is pretty much what a new SL should be. It does what the last one did, but does it better in nearly every way apart from the lingering thought that there's a touch too much technology clouding the clarity of the relationship. Personally, though, I'd enjoy a Jaguar XKR convertible more, because the driving experience feels somehow more, well, organic.

Which brings us back to the beginning, and the delicious 300SL Roadster I also drove. Here's how it's better than the new SL. It's more compact and easier to see out of. It's easier to place in a bend because its steering talks to you more. You feel a part of the driving process thanks to the analogue purity of the throttle response and the mechanical neatness of its lovely manual gearchange. It doesn't have an excess of grip. And its style has already lasted a half century with honours.

Yes, it pollutes more and would be less benign in a crash; undoing half a century of public opinion's evolution here is impossible. And the $665,000 or so you'll need for a decent one will buy half a dozen new SLs. I guess the new SL500 is a car for its time just as the 300SL was a car for its own era, but – value apart – there's no reason why the old-timer should be any less usable today than the new one provided you have the right enthusiast mindset. In which case, you'll surely enjoy it more.